TWI Industrial Member Report Summary 169/1981
By S Elliott
The work reported here covers part of a broad research programme carried out to investigate the mechanical properties of welds made by non-arc processes, particularly with respect to the process parameters. This part of the programme is an investigation into the toughness of electron beam welds, as measured by the Charpy impact test. A range of C and C-Mn steel compositions was examined and the weld toughness assessed in relation to variations in welding speed and weld width, the two main process related variables for electron beam welding. It was found that the fusion zone microstructures could be strongly influenced by suitable variation of the process parameters. The variation of toughness caused by these changes was not clarified by toughness testing using the Charpy V-notch test. This method of toughness testing was found to have severe limitations for the testing of narrow welds as for welds having a width <2.5mm, the fracture path tends to deviate away from the weld metal, giving a false indication of absorbed energy for the weld. Crack tip opening displacement (CTOD) testing is recommended for future work.